JP2001142195A - Proximity effect correction mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a proximity effect correction mask which is capable of correcting an optical proximity effect without being affected by the space from a rectangular pattern on an adjacent mating side. SOLUTION: The four sides of the rectangular pattern 4 of the proximity effect correction mask for transferring the mask patterns consisting of the opaque rectangular pattern 2 and the transparent space pattern 3 are enclosed by the translucent phase shift 4. The width (W1<W2) of the phase shift pattern 4 on the long side 2a side of the rectangular pattern and the phase shift pattern 4 on the short side of the rectangular pattern and the phase difference between the exposure light transmitted through the space pattern 3 on the short side 2b side and long side 2a side of the rectangular pattern 2 and the exposure light of the phase shift pattern 4 are varied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask used for a projection exposure apparatus, and more particularly to a proximity effect correction mask used for forming a fine pattern in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art Conventionally, as a photomask of this type,
There is one disclosed in Japanese Patent No. 2917879.
The photomask disclosed in Japanese Patent No. 2917879 is a photomask that transfers a rectangular pattern having a long side and a short side, and a tip of the rectangular pattern on the short side is used as a base of the photomask. It is composed of only a semi-transparent film that generates a phase difference of 180 degrees between the light transmitted through the transparent substrate and a region other than the front end portion of the rectangular pattern is provided with a light-shielding film.

According to the photomask disclosed in Japanese Patent No. 2917879, a phase difference of 180 degrees is caused between the front end of the short side of the rectangular pattern and the light transmitted through the transparent substrate forming the base of the photomask. The light transmitting through the translucent film and the transparent substrate forming the base of the photomask are transmitted by providing the light shielding film in the area other than the short-side end of the rectangular pattern. The generated light interferes with each other and cancels out each other, so that the light intensity at the end of the translucent film can be made steep, and a desired pattern shape can be transferred.

[0004]

However, according to the photomask disclosed in Japanese Patent No. 2917879, the depth of focus can be improved, but the pattern width on the long side of the rectangular pattern fluctuates. There is a problem that it is.

As a result of technical analysis to solve this problem, when a rectangular pattern and a space pattern are arranged adjacent to each other, an optical proximity effect occurs, and this effect is generated on the long side of the rectangular pattern. It was found that this was the cause of the pattern width fluctuation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a proximity effect correction mask which can correct an optical proximity effect without being influenced by a space between adjacent rectangular patterns.

[0007]

According to the present invention, there is provided a proximity effect correction mask for transferring a mask pattern including an opaque rectangular pattern and a transparent space pattern. Surrounding the four sides of the rectangular pattern with a translucent phase shift pattern, the width of the phase shift pattern on the long side of the rectangular pattern and the width of the phase shift pattern on the short side of the rectangular pattern,
The phase difference between the exposure light transmitted through the space pattern and the exposure light transmitted through the phase shift pattern is different between the short side and the long side of the rectangular pattern.

The width of the phase shift pattern on the short side of the rectangular pattern is set wider than the width of the phase shift pattern on the long side of the rectangular pattern, and the phase shift pattern and the space pattern on the short side of the rectangular pattern are set. Inverts the phase difference on the short side of the exposure light that passes through, and on the long side of the exposure light that has passed through the space pattern and the exposure light that has passed through the phase shift pattern on the long side of the rectangular pattern. Is set smaller than the phase difference on the short side.

The phase difference on the long side is set in the range of 60 to 90 degrees.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing a proximity effect correction mask according to an embodiment of the present invention.

In the proximity effect correction mask shown in FIG. 1 according to an embodiment of the present invention, opaque light-shielding patterns 2 and transparent space patterns 3 are alternately arranged on a transparent substrate 1 serving as a base of a photomask. (L (line) / S
(Space) pattern).

The light shielding pattern 2 includes a long side 2a and a short side 2a.
It is formed in a rectangular pattern shape having b. The shape of the light-shielding pattern is not limited to a rectangular pattern, but may be a belt-like long shape, or any shape as long as it is a rectangular pattern having a long side 2a and a short side 2b.

In the embodiment of the present invention shown in FIG. 1, four sides (squares) of a light-shielding pattern 2 as a rectangular pattern are surrounded by a semi-transparent phase shift pattern 4, and the phase shift pattern 4 on the long side 2a of the light-shielding pattern is Shading pattern short side 2b
The width W1 and the width W2 of the phase shift pattern 4 on the side and the space pattern 3 on the long side 2a side and the short side 2b side of the light shielding pattern.
And a phase difference between the exposure light transmitted through the phase shift pattern 4 and the exposure light transmitted through the phase shift pattern 4.

In the embodiment of the present invention, the phase shift pattern 4 on the long side 2a of the light shielding pattern and the short side 2b of the light shielding pattern
To make the phase difference different from the widths W1 and W2 of the phase shift pattern 4 on the side of the light shielding pattern, the width W2 of the phase shift pattern 4 on the side of the light shielding pattern short side 2b is changed to the width W1 of the phase shift pattern 4 on the side of the light shielding pattern long side 2a (W1 <W
2) The phase shift pattern 4 on the short side 2b of the rectangular pattern
Side 2b of the exposure light transmitting through the space pattern 3
And the phase difference between the exposure light transmitting through the space pattern 3 on the long side 2a of the rectangular pattern and the exposure light transmitting through the phase shift pattern 4 on the long side 2a is determined on the short side 2b side. This is realized by setting the phase difference to be smaller than.

Next, the technical support of the present invention will be described. At the time of exposure, the light transmitted through the transparent space pattern 3 of the proximity effect correction mask is diffracted and interferes with each other. It is affected by pattern 2 or space pattern 3.

Therefore, an error occurs between the shape of the transferred image of the mask pattern by the space pattern 3 and the light shielding pattern 2 of the proximity effect correction mask and the designed pattern size.

FIG. 2 shows that the width W3 of the light shielding pattern 2 is 0.1
8 μm, the width W1 of the phase shift pattern 4 on the long side 2a of the light-shielding pattern is 0.10 μm, and the width W4 of the space pattern 3 between the adjacent phase shift patterns 4 is changed. The change in light intensity at the mask edge due to the change in W4 is shown.

In the embodiment of the present invention, a semi-transparent phase shift pattern 4 is added to four sides of the rectangular light-shielding pattern 2, and the phase shift pattern 4 is provided. The light transmitted through the pattern 4 has a phase difference with respect to the light transmitted through the transparent space pattern 3. Thereby, the diffraction and mutual interference of the light transmitted through the proximity effect correction mask change, and the proximity effect changes.

Specifically, on the short side of the rectangular light shielding pattern 2 according to the embodiment of the present invention, the width W2 of the phase shift pattern 4 on the short side 2b of the light shielding pattern is changed to the phase W on the long side 2a of the light shielding pattern. By setting the width to be wider than the width W1 of the shift pattern 4 (W1 <W2), the phase difference on the short side 2b of the exposure light transmitted through the phase shift pattern 4 and the space pattern 3 on the short side 2b of the rectangular pattern is inverted. To reduce the change in pattern size due to the proximity effect,
Is corrected on the short side 2b side.

When the phase difference between the light transmitted through the phase shift pattern 4 and the light transmitted through the space pattern 3 on the short side 2b of the light-shielding pattern on the short side of the rectangular light-shielding pattern 2 is set to 180 degrees, the light is blocked. Short side 2 of pattern 2
The tip of b is expanded, the shrinkage on the short side 2b of the light shielding pattern 2 is eliminated, and the dimensional error is corrected.

In FIG. 2, a line having a phase difference of 0 degrees indicates a case where no phase shift pattern is provided around the light shielding pattern 2. As shown in FIG. 2, when the phase difference is 0 degree, no problem occurs when the width W4 of the space pattern 3 between the adjacent phase shift patterns 4 is wide, but when the width is narrow, the edge light intensity largely changes. Therefore, the width W3 of the light shielding pattern 2 fluctuates, and the phase shift pattern 4
Is changed, the width W4 of the space pattern 3 is changed.
Changes the edge light intensity.

When the phase difference between the light transmitted through the phase shift pattern 4 and the light transmitted through the space pattern 3 is changed on the long side 2a of the light shielding pattern 2, the space pattern 3
Of the light shielding pattern 2 in the range of the phase difference of 30 to 90 degrees as is apparent from FIG.
As a result of the experiment, it was found that the dimensional change of the width W3 of the sample tended to be small.

When the experimental results are further analyzed, as is clear from FIG. 2, the phase difference between the light transmitted through the phase shift pattern 4 and the light transmitted through the space pattern 3 on the short side 2b of the light shielding pattern is set to 180 degrees. As a result, the edge light intensity is adjusted to the space pattern 3 between the light shielding patterns 2.
Is improved around A of 0.55 μm, that is, the light intensity on the long side 2a of the light shielding pattern is improved. As a result, the width of the light shielding pattern 2 on the long side 2a of the light shielding pattern 2 is improved. It has been found that the reduction or expansion of the width W4 is eliminated and the dimensional error is corrected.

Therefore, on the long side of the rectangular light shielding pattern 2 according to the embodiment of the present invention, the width W2 of the phase shift pattern 4 on the short side 2b of the light shielding pattern is changed to the phase shift pattern on the long side 2a of the light shielding pattern. 4 is set wider than the width W1 (W1 <W2), and the phase difference on the short side 2b of the exposure light passing through the phase shift pattern 4 and the space pattern 3 on the short side 2b of the rectangular pattern is inverted. Specifically, the phase difference is adjusted to 180 degrees, and the phase difference on the long side 2a between the exposure light transmitted through the space pattern 3 and the exposure light transmitted through the phase shift pattern 4 on the long side 2a of the rectangular pattern is adjusted. The phase difference on the long side 2a is set to be smaller than the phase difference on the short side 2b, specifically, the phase difference on the long side 2a is set in a range of 30 to 90 degrees. ) Is the phase difference on the short side 2b side (180 degrees), the change in pattern size due to the proximity effect is reduced, the reduction or expansion of the width W3 on the long side 2a of the rectangular pattern 2 is suppressed, and the space pattern 3 of the proximity effect correction mask and An error generated between the shape of the transferred image of the mask pattern by the light-shielding pattern 2 and the designed pattern size is suppressed to be small.

[0026]

As described above, according to the present invention, it is possible to provide a proximity effect correction mask capable of correcting an optical proximity effect irrespective of the space between adjacent rectangular patterns.

[Brief description of the drawings]

FIG. 1 is a plan view showing a proximity effect correction mask according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram illustrating a change in light intensity at a mask edge based on a change in the width of a space pattern of a spatial image projected on the proximity effect correction mask according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 transparent substrate 2 light shielding pattern 3 space pattern 4 phase shift pattern

Claims (3)

[Claims] 1. A proximity effect correction mask for transferring a mask pattern comprising an opaque rectangular pattern and a transparent space pattern, wherein four sides of the rectangular pattern are surrounded by a translucent phase shift pattern, and the rectangular pattern length is The width of the phase shift pattern on the side and the width of the phase shift pattern on the short side of the rectangular pattern, and the exposure light and the phase shift pattern transmitted through the space pattern on the short side and the long side of the rectangular pattern. A proximity effect correction mask having a phase difference from exposure light. 2. The width of the phase shift pattern on the short side of the rectangular pattern is set wider than the width of the phase shift pattern on the long side of the rectangular pattern, and the phase shift pattern and the space on the short side of the rectangular pattern are set. Inverts the phase difference on the short side of the exposure light transmitted through the pattern, and the long side of the exposure light transmitted through the space pattern and the exposure light transmitted through the phase shift pattern on the long side of the rectangular pattern. 2. The proximity effect correction mask according to claim 1, wherein the phase difference at the short side is set smaller than the phase difference at the short side. 3. The proximity effect correction mask according to claim 2, wherein the phase difference on the long side is set in a range of 60 to 90 degrees.